The use of pit and fissure sealants is a promising treatment in the attempt to combat occlusal caries. The question of possible progression or arrestment of caries under the sealant has been addressed by the principal investigator and co-workers who confirmed that sealed caries bocome sterile and do not progress. The long range objective of this program is to assist the practicing dentist and the scientific community in seeking improved methods if treating dental caries. Fluorides give best protection to cleaned smooth surfaces of teeth because direct contact with clean enamel facilitates incorporation of fluoride into enamel. Deep pits and fissures, however, remain selectively inaccessible to the toothbrush, contain bacterial and other debris, remain rather inaccessible to the fluoride ion, and are therefore more vulnerable to caries. The specific aim of this research is to carry out a clinical study on the evaluation of a filled sealant as a conservative restorative material for small occlusal (Class I) carious lesions without cavity preparation, using procedures developed in a previous research project. Approximately l50 children with two Class I lesions will be treated. One lesion will be restored with a quartz-filled sealant and the other with a high copper amalgam. The efficacy of such treatments will be assessed by clinical evaluations using Ryge's criteria and by using a newly developed standardized radiographic procedure at 0,6,18 and 36 month evaluation periods. If the filled sealant restoration is judged clinically equivalent in anatomic form and marginal integrity to the amalgam restoration and radiographically acceptable after 3 years, no further treatment may be required. The proposed research is designed to determine the feasibility and efficacy of such a restorative treatment program. If results are satisfactory, this study will provide methodology applicable to the public health dentist and to the private practitioner as a simple, conservative method of treatment for small carious lesions.